1. Field of the Invention
The present invention relates to an umbilical member guide mechanism at a front end of a wrist of an industrial robot.
2. Description of the Related Art
At a wrist part of an industrial robot etc., an umbilical member guide mechanism which guides a plurality of umbilical members, which are led from an arm side to the wrist part of the robot, to a tool which is attached to the front end of the wrist is considered necessary. The umbilical member guide mechanism is configured to guide the plurality of umbilical members via the outside of the wrist part to the tool or is configured to guide the plurality of umbilical members via the inside of the wrist part to the tool.
Japanese Unexamined Patent Publication No. 2001-150382 A1 discloses a configuration which uses a bracket from which a plurality of umbilical members are suspended together by a spring so as to guide the plurality of umbilical members via the outside of the wrist part to the tool. Furthermore, Japanese Unexamined Patent Publication No. 2002-79487 A1, Japanese Unexamined Patent Publication No. 10-329079 A1, and Japanese Patent No. 3739756 disclose configurations which guide a plurality of umbilical members to a hollow part which is positioned at a center of rotation of the front end of the wrist of a robot.
However, the prior art has the following problems.
In both a configuration guiding the members via the outside of the wrist part and a configuration guiding the members via the inside of the write part, the motion range of a final output shaft part of the front end of the wrist (tool mounting surface side) is limited by the durability of the laid umbilical members. Such a limitation on the motion range is the usually the same extent in the plus direction and minus direction from the reference position.
However, when a robot is actually used, often the motion range of the final output shaft part is not the same extent in the plus direction and minus direction from the reference position, that is, a motion range biased to either the plus direction or minus direction is demanded. For example, when the motion range of the final output shaft part is limited to ±180°, but in actuality use from −100° to +225° is demanded, due to the limitation on the motion range, there will be a range where operation is not possible. In such a case, it is necessary to change the mounting phase of the tool which is mounted at the front end of the wrist so as to match with the required motion range.
However, to change the mounting phase of a tool, some measure has to be taken at the tool side. The phase of a tool with respect to the final output shaft part is positioned by for example pins. In such a case, to change the mounting phase of the tool, it is necessary to change to another tool of the same shape but different pin positions.
For this reason, detaching a tool and attaching another tool takes time. Further, when further changing the motion range by changing the mounting phase of a tool again, it is necessary to prepare tools further different in pin positions.
Furthermore, when the motion range changes in a configuration guiding the members via the outside of the wrist, it is necessary to change the fastening position of the umbilical members. Therefore, the motion of the umbilical members also change. For this reason, there is a possibility of umbilical members interfering with the peripheral equipment. Further, there is also the problem of an unexpected load acting on the umbilical members and the umbilical members greatly falling in durability.
The present invention was made in view of this situation and has as its object the provision of an umbilical member guide mechanism which enables a motion range of a final output shaft part of a front end of a wrist of a robot to be easily changed as desired without umbilical members interfering with peripheral equipment and without causing a drop in the durability of the umbilical members.